OpenAI to Watermark ChatGPT and Codex Text in EU

OpenAI said October 5, 2026 it will add an invisible watermark to ChatGPT and Codex text in the European Union to comply with the EU AI Act. The pattern shapes word choices, survives copy-paste, and will roll out over the coming weeks. API developers globally can opt in, but OpenAI is not making watermarking a global default.